集约化种植区硝态氮在土壤剖面中的分布与累积特征

采用GPS定位、土钻取样的方法,在北京市大兴区14个乡镇的农田土壤中选取了91个土壤剖面,分别在0～20cm、20～40cm、40～60cm、60～80cm4个不同深度取得土壤样品,并在一次种植期结束后,综合考虑种植类型和土壤质地后选取24个重复取样点.在此基础上,分析了种植类型及土壤质地对硝态氮分布及累积情况的影响.结果表明,研究区土壤中的硝态氮含量有随土壤深度的增加呈降低的趋势.露地菜田和设施菜田最容易出现硝态氮淋洗现象,果园和粮田的总体状况较好,但粮田个别地区有一定的污染风险,细质地土壤具有较强的保水保肥能力.大兴区采育镇及长子营镇地区有较高的硝态氮累积量,为硝态氮淋洗污染危险区,应进行合理施肥,以免在一个种植期结束后造成较深层土壤中硝态氮的累积.研究结果可为大兴区地下水环境保护提供参考.     

广州市“南肺”果园土壤H g和A s的形态分析

采用Tessier连续提取法、BCR连续提取法和Leleyter连续提取法,研究广州"南肺"果园土壤Hg和As的形态分布和生物可给性。结果表明,果园土壤Hg和As形态分布都以残渣态为主;3种方法的土壤生物可给性分析均表明,Hg和As生物可利用态的含量较少;生物不可利用态是主要形态,其次是潜在可利用态。     

紫外辐射H2O2与PMS氧化准好氧矿化垃圾床渗滤液尾水

采用紫外（UV）活化双氧水（H₂O₂）和过一硫酸盐（PMS）产生活性氧物种降解准好氧矿化垃圾床渗滤液尾水中有机污染物.结果表明,紫外辐射双氧水（UV-H₂O₂）和紫外辐射过一硫酸盐（UV-PMS）体系对有机污染物的降解相比于单独体系效果显著.初始pH值和氧化剂投加量能够显著影响2种体系的降解效能,增加氧化剂投加量能够一定程度提高2种体系对渗滤液尾水中有机物的去除;2种体系均在酸性条件下效果较好,初始pH值的升高对2种体系过程有机物降解有抑制作用并且对UV-H₂O₂体系的抑制尤为显著.在最优条件下（初始pH值为3,氧化剂投量为0.084mol/L）,UV-H₂O₂与UV-PMS体系处理后出水COD去除率分别达到了72.09%和56.22%.另外,UV-H₂O₂体系中主要活性氧物种是羟基自由基,而UV-PMS体系中主要是由羟基自由基和硫酸根自由基的共同作用.紫外-可见光谱与三维荧光光谱表明两体系中均能降解渗滤液尾水中难降解芳香类有机物质,并且UV-PMS较UV-H₂O₂体系对腐殖质的反应速率更快,但是两种体系对渗滤液尾水中腐殖质的降解途径存在显著差异.研究结果可为光化学氧化处理垃圾渗滤液中难降解有机物提供参考.     

京津冀臭氧变化特征及与气象要素的关系

基于2014~2017年京津冀13座城市的O₃-8h数据,分析O₃时间变化特征及污染状况.在此基础上,结合同期气象数据研究近地层O₃浓度与气象要素的关系.结果表明：2014~2017年京津冀区域O₃-8h整体呈上升趋势,增长率为4.50μg/m³.区域内O₃污染整体加重,北京、保定O₃污染较为严重;2014~2015年O₃浓度与超标情况的月变化主要呈单峰型变化,峰值出现在5月;而2016~2017年为不规则双峰型变化,峰值出现在5~6月和9月.与气象因子的相关性表明：气象要素对O₃的影响具有明显的季节差异,其中春、夏、秋季气温是影响O₃浓度变化的主要因素,而在冬季相对湿度与风速为影响O₃浓度变化的主要因素.此外,分析表明北京、天津、石家庄3大城市夏季形成高浓度O₃的阈值明显不同.     

TiO2/pg-C3N4复合催化剂的制备及光催化性能

通过简单的超声剥离分散和水热法,成功制得了具有多孔结构的TiO₂/pg-C₃N₄复合催化剂.利用XRD、SEM、TEM、UV-Vis DRS和PL对样品的形貌、结构及光学性能进行了表征.在模拟太阳光照射下,以RhB和MO为模拟污染物考察了TiO₂/pg-C₃N₄的光催化性能.结果表明：当TiO₂占pg-C₃N₄的质量分数为5%时,制得的TiO₂/pg-C₃N₄（5：100）复合催化剂具有最优的光催化性能.TiO₂/pg-C₃N₄（5：100）对RhB的光催化降解途径为O^2·-和h⁺使整个共轭发色团结构发生裂解.TiO₂/pg-C₃N₄（5：100）光催化性能的提高一方面是由于多孔结构增加了光催化反应的活性位点;另一方面是由于TiO₂与pg-C₃N₄之间形成了Z型异质结,与传统的Ⅱ型异质结相比,该复合催化剂不仅使光生载流子分离效率提高,同时保留了pg-C₃N₄导带电子的强还原性和TiO₂价带空穴的强氧化性.     

Water incubation-induced fluctuating release of heavy metals in two smelter-contaminated soils

The soil moisture regime can affect the release of heavy metals in soil. In the previous studies, slightly polluted soils or artificially contaminated soil samples were considered to investigate the effect of soil moisture. We used highly smelter-contaminated and aged soils to study the release of typical heavy metals(Cu, Zn, Cd and Pb) induced by water incubation in batch experiments with characterization via speciation and X-ray diffraction analyses(XRD). The results show that the leachable concentrations of the heavy metals increased slightly in the first 30 days, decreased drastically between 30 and 90 days, and immobilized relatively constant thereafter. The fluctuation was ascribed to the changes of soil Eh and pH, the reductive dissolution of crystalline iron oxides, the formation of new amorphous iron oxides, the absorption of dissolved organic matter and the precipitation of metal sulfide. Speciation analysis indicated that a proportion of the soil heavy metals was transformed from an exchangeable fraction to a less labile fraction after water incubation. And the presence of a lead iron oxide phase and the peak increasing of zinc sulfide were observed via XRD analyses. Finally, water incubation restrained the release of heavy metals after 180 days of incubation, and reduced the leachability of Cu, Zn, Cd and Pb by as much as 1.61%–7.21% for soil A and 0.43%–3.36% for soil B, respectively. The study findings have implications for the formulation of risk control and management strategies for heavy metals in smelter-contaminated soils.     

典型肥料生产场地氨氮分布特征及风险控制目标确定

为探究肥料生产场地的NH₃-N（氨氮）分布特征及环境风险,以我国某肥料生产场地为研究对象,在场地调查基础上,对场地土壤和地下水NH₃-N的空间分布进行分析,并以人体健康和场地地下水为保护对象分别讨论了土壤NH₃-N风险控制目标值的计算方法.结果表明:①目标场地土壤中w（NH₃-N）为0.03~15 000 mg/kg,水平方向上高值区集中分布于核心生产区及原辅料堆场,垂向上总体表现为由上至下随深度增加呈先逐步升高后降低的趋势,并且富集于人工填土与原状粉质黏土交界处,粉质黏土阻碍NH₃-N向下迁移,并随地层结构变化其迁移深度不同.②场地上层滞水和潜水中ρ（NH₃-N）分别为19.10~3 320和0.03~219 mg/L,超标率分别为100%和57.89%,并且地下水与土壤的NH₃-N在水平空间分布上具有重叠特征.③因NH₃-N主要通过呼吸吸入挥发性气体产生暴露,并且仅有经呼吸暴露的毒性参数,故采用《污染场地风险评估技术导则》中经呼吸暴露途径的非致癌效应风险控制值计算模型来计算土壤NH₃-N的控制目标,通过代入场地实测土壤K_d（土-水分配系数）,得到居住用地下的土壤NH₃-N控制目标值为9 195 mg/kg;若考虑保护地下水水质安全,据三相或两相平衡模型耦合NH₃-N在包气带衰减和地下水稀释作用,当目标场地地表无积水的入渗条件下得到的控制目标值为6 203 mg/kg;当地层从上至下呈饱和含水条件时,土壤NH₃-N控制目标为811 mg/kg.计算值可用作不同场地进行土壤NH₃-N风险管控的参考目标,实际应用中可结合不同地块环境条件、不同受体和保护目标,选择相应的风险控制值对场地进行风险管控.此外,土壤和地下水的NH₃-N污染控制均可考虑采用工程措施和制度控制来进行.      

环渤海地区生态效率评价及空间演化规律

运用三阶段DEA模型对环渤海沿海地区17个城市的生态效率进行测算,并结合标准差椭圆和重心坐标方法,定量分析了2006-2015年环渤海地区生态效率的空间演化规律。结果表明：（1）基于三阶段DEA模型测算的生态效率结果,环渤海沿海17市的生态效率总体呈中等偏上水平,且2006-2015年效率值持续上升,天津、唐山、青岛、大连位居前四,17市中绝大多数城市生态效率值低于环渤海平均值,地区差异十分显著。（2）标准差椭圆结果显示环渤海沿海地区生态效率整体呈东北—西南格局,且有逐渐向西南偏移的趋势。（3）环渤海地区生态效率存在明显的省际差异性,且各省限制性因素区别较大。     

Development of a model to simulate soil heavy metals lateral migration quantity based on SWAT in Huanjiang watershed, China

Lateral transportation of soil heavy metals in rainfall events could significantly increase the scope of pollution. Therefore, it is necessary to develop a model with high accuracy to simulate the migration quantity of heavy metals. A model for heavy metal migration simulation was developed based on the SWAT(Soil and Water Assessment Tool) model. This model took into consideration the influence of soil p H value, soil particle size, runoff volume, sediment amount,concentration of water-soluble heavy metals dissolved in runoff and insoluble absorbed to the soil particles. This model was reasonable in Huanjiang watershed, Guangxi Zhuang Autonomous Region, south China, covering an area of 273 km~2. The optimal drainage area threshold was determined by analyzing the effects of watershed subdivision on the simulation results to ensure the simulation accuracy. The main conclusions of this paper were:(1) watershed subdivision could affect simulation migration quantity of heavy metals;(2) the quantity of heavy metals transported by sediment accounted for 97%–99% of the total migration quantity in the study watershed. Therefore, sediment played the most important role in heavy metal migration;(3) the optimal drainage area threshold percentage to ensure high simulation accuracy was determined to be 2.01% of the total watershed;(4) with the optimal threshold percentage, this model could simulate the migration quantity of As, Pb and Cd accurately at the total watershed and subwatershed level. The results of this paper were useful for identifying the key regions with heavy metal migration.     

Ecotourism Model and Benefits of Periphery Regions in Western Sichuan Province

There are many problems in the minority regions of western Sichuan Province, such as serious soil erosion, fragile ecological environment, low levels of economy and so on. Ad-vantages of tourism resources in the "periphery regions" should be fully utilized, and "multi-tourism" meets the characteristics and present situation of the minority regions. The "multi-tourism de-velopment model" can exert the functions of tourism as the key industry. Based on the demands and the internal linkages among different industries, the model can accelerate the development of related-industries, such as eco-agriculture, eco-industry and so on. Through implementing the multi-tourism model, we can fully utilize the advantages of the periphery regions and promote the sustainable development of regional economy.